Method and device for producing by electrophoresis fully ceramic tooth element having a predefined spatial shape

ABSTRACT

The invention relates to a method and device for producing by electrophoresis fully ceramic tooth elements having a predefined spatial shape, wherein an electric conductive plate ( 1 ) having different conductive areas is applied to a working model or a structural element directly or at a certain distance. According to a known method, a power is supplied to the plate by means of a cable, which is removable after coating by means of a slip and prior to sintering. According to the inventive method, said laborious operation is nor required anymore. The inventive method consists in fixing the plates ( 1 ) to a conductive tooth stump ( 2 ) by means of an adhesive conductive material ( 5 ) or to an implant abutment ( 3 ). The power can be supplied by the tooth stump, the abutment or a leg ( 7 ) integrateable with the plate. Said plate is preferably made of zinc or an adhesive conductive material, preferably a mixture of wax and zinc powder which disappears without residues by sintering. A plate which is particularly suitable for carrying out said method and whose conductivity variations are obtainable by means of recesses embodied therein is also disclosed.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a submission to enter the national stage under 35 U.S.C. 371 for international application number PCT/DE2006/000002 having international filing date 3 Jan. 2006 for which priority was based upon patent application 10 2005 006 624.0 having a filing date of 12 Feb. 2005 filed in Germany.

STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH AND DEVELOPMENT

(Not Applicable)

REFERENCE TO AN APPENDIX

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BACKGROUND OF THE INVENTION

From WO 2004/041113 A1, a method for the production of fully ceramic tooth elements, by means of electrophoresis, is known, in which an electrically conductive chip placed, directly or at a distance on a working model or a structural element, for example, an implant-abutment, wherein the chip has different conductivities. Any desired spatial shape can be directly attained with the method with a corresponding selection of the chip and without a great deal of reworking. With this known method, power is supplied to the chip or chips by means of a cable.

After coating with slip, it is necessary to separate the cable from the chip. It should be obvious to the specialist that this cannot be done without a certain amount of effort, since a damaging of the applied slip layer is unavoidable. In order to produce satisfactory green bodies, a certain amount of reworking therefore is necessary.

BRIEF SUMMARY OF THE INVENTION

Therefore, the goal of the invention indicated in claim 1 is to refine the electrophoresis method known from WO 2004/041113 A1 in such a way that a reworking is no longer required. This goal is attained with the method features of claim 1. Advantageous embodiments are described in the dependent claims.

The invention also concerns the constructive development of the chips that are particularly suitable for the claimed method.

For the terminology below, one should also note that the term “slip,” as used in dental practice, is understood to mean a paste of ceramic powder in a primarily aqueous suspension liquid. Furthermore, the term “working model” refers to the meaning common for a dental technician. Therefore, it is not a model duplicated by the working model. This statement is of importance in that other electrophoresis methods not developed by the inventor work only with duplicated models, since the specialist knows that aside from the additional work, any duplicating produces additional errors, which have to be removed in tedious reworking. It is obvious, however, that the claimed method can also be carried out on a duplicated model.

The invention is explained in more detail with the aid of FIGS. 1 to 8.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a FIG. 1, a section with two tooth stumps, sawed out of a working model.

FIG. 2, a section with two implant abutments.

FIG. 3, a section with a tooth stump and an implant abutment.

FIG. 4, a section also with a tooth stump and an implant abutment in another arrangement.

FIG. 5, a chip for the production of a front tooth.

FIG. 6, a chip for the production of molar teeth.

FIG. 7, a chip for the production of premolar teeth.

FIG. 8, a chip for the production of a canine tooth.

DETAILED DESCRIPTION OF THE INVENTION

From the teeth of a patient, a working model is first prepared in the usual manner. From this working model, the section is sawed out, in which the restoration of the teeth is to take place. FIGS. 1 to 4 show, schematically, four such different sections of working models, on which a ceramic structure, for example, from alumina, is to be built by electrophoresis. These sections are fixed in a holder of the electrophoretic coating machine and coated by immersion in the aqueous slip, wherein they are turned 180° from the position shown in the drawings.

FIG. 1 shows a section of a working model with two tooth stumps 2. A chip 1 is affixed between these tooth stumps by means of a conductive adhesive material 5. This material can consist of dental wax, as used for the fixing of parts in a dental laboratory. In this wax, 5 g zinc powder per 1 g wax are worked in. In the development of the invention, it was surprisingly discovered that different waxes produce different conductivities with the same mixture ratio of zinc power to wax, although wax alone is not conductive.

Since, as a rule, a working model is made of gypsum or another nonconductive material, the surface of the tooth stumps must be rendered conductive. This is done by the application of a conducting lacquer, the conductivity of which is also attained by zinc powder. Silver conducting lacquers that are common in dental practice are less suitable, since they do not volatilize residue free during sintering. So that the green body can be removed without problems from the model after electrophoresis, coating of the model with a release agent is indicated, as is taught in DE 198 12 664 A1. In FIG. 1, power is supplied via a tongue 8.

The chip itself is preferably made of zinc. Here, the desired shape is cut out of zinc foil with a laser. Since zinc can easily be shaped in a lasting manner, a prefabricated chip is adapted to the local need by bending or by cutting the material. Thus, during electrophoresis, the desired spatial shape is already formed, and requires only a small amount of reworking, if any.

After drying and removing the model, the green body is sintered according to known methods. Here, another advantage of the zinc as material for the chip 1 and the adhesive wax 5 is shown, since it volatilizes residue free at the high sintering temperature.

In FIG. 2, the model shows two implant abutments 3, which are usually made of titanium and are thus conductive. The supply of power can take place in this case via a connector 6, which is connected conductively to an abutment 3.

FIG. 3 shows an abutment 3 and a tooth stump 2. After the tooth stump 2, as described above, has been rendered conductive, the supply of power can take place via a leg 7 of a chip. As is shown in FIGS. 5 to 8, the chips always have this leg 7 in the original shape; the leg is also useful for easier handling of the chip and is cut off when it is not needed.

FIG. 4 shows that a chip can be affixed on another chip with the adhesive wax 5. The supply of power takes place via the connection 6 to the abutment 3. The tooth stump 2 is rendered conductive, as was already described above.

From the preceding statements, it is clear that any structure is possible with the invention because of its versatility.

FIGS. 5 to 8 show different chips in the original shape, enlarged 2×. FIG. 5 shows a chip for the production of a front tooth. According to FIG. 6, the chip is used for the production of a molar tooth; according to FIG. 7, for a premolar tooth. A canine tooth can be produced with the chip according to FIG. 8.

As all figures show, areas of different conductivities are produced in the chips by means of recesses 4. The chips also have a leg 7, which is used for better handling, but can also be used as a conductor for the electric current. 

1. A method for the production of fully ceramic tooth elements with a predefined spatial shape, by means of electrophoresis, wherein an electrically conductive chip (1) is placed on a working model (2) or on a structured element (3) directly or at a distance, and the chip has areas (4) of different conductivities, characterized in that the supply of current to at least one chip (1) takes place via a conductive adhesive material (5).
 2. A method according to claim 1, characterized in that with implant-abutments, the chip is adhesively affixed to at least one abutment and the supply of current takes place via the abutment.
 3. A method according to claim 1, characterized in that with a nonconductive working model (2), at least one tooth stump is coated with a metal-containing film, which dissolves without residue during the sintering.
 4. A method according to claim 3, characterized in that zinc is used as the metal for the coating.
 5. A method according to at least one of claims 1 to 4, characterized in that the supply of current takes place via a leg (7) of the chip.
 6. A method according to at least one of claims 1 to 4, characterized in that the conductive, adhesive material is made of a mixture of wax and a zinc metal powder.
 7. An electrically conductive chip having areas (4) of different conductivities, the chip being for use in the production of fully ceramic tooth elements with a predefined spatial shape by means of electrophoresis, wherein the chip is placed on a working model (2) or on a structured element (3) directly or at a distance, and current is supplied to the chip (1) via a conductive adhesive material (5), the chip characterized by areas of different conductivities produced in the chip by recesses.
 8. A chip according to claim 7, characterized in that it is made of zinc.
 9. A chip according to claims 7 or 8, characterized by a thickness of 0.03 to 0.15 mm.
 10. A chip according to one of claims 7 to 8, characterized in that it is cut out of metal foil by means of a laser. 